I've never seen this.  Since a retail bakery is using it, I'm assuming it's readily available.  I'm attaching a link to Dawn's site for videos.  Watch the Wedding Cake Production one.

http://www.bakemag.com/videos/discovering%20americas%20bakeries.aspx

Interesting - looks like a pvc pipe to me. That certainly wouldn't collapse, and it would be relatively cheap.

Also interesting that she iced the top tier after it was already stacked.

It did sort of look like PVC pipe, but it was thinner, I think.  PVC is kinda thick.  

And yeah, I could never ice a tier that's already sitting on top of a finished tier.  I've seen a few oldtimers do it, but I certainly can't!

I wasn't able to find the video but are you talking about Cake Frame?

Very interesting, @leah_s! It does look like PVC pipe. I googled and found a few blogs that talked about using PVC, as in the image below. My only question: Is it food safe? Especially since the pipes are cut and the contents exposed.

There are different types of PVC. I would think if you are using the same PVC that is used for water lines - like the kind that run to your kitchen sink - they would be food safe.

I would think that the pipe manufacturers would use the same food-safe PVC for inside and outside, to save having to faff around too much. Unless the inside of the pipes are coated with something special on top of regular plastic/PVC. We would have to ask a proper expert opinion though, I'm just guessing...

Well I don't know. Maybe PVC is food safe, maybe not. But I sure wouldn't use it when working with edibles and I don't recommend anyone trolling the aisles for products used in the construction trades. I was at Home Depot this morning and asked about this. Two contractors and a plumber thought it was a crazy/scary question, given that construction materials are not formulated to be food safe. 

Vinyl chloride (CH2=CHCl), also known as chloroethylene, is most often obtained by reacting ethylene with oxygen and hydrogen chloride over a copper catalyst. It is a toxic and carcinogenic gas that is handled under special protective procedures. PVC is made by subjecting vinyl chloride to highly reactive compounds known as free-radical initiators. 

Before PVC can be made into finished products, it always requires conversion into a compound by the incorporation of additives (but not necessarily all of the following) such as heat stabilizers, UV stabilizers, plasticizers, processing aids, impact modifiers, thermal modifiers, fillers, flame retardants, biocides, blowing agents and smoke suppressors, and, optionally pigments.[8] The choice of additives used for the PVC finished product is controlled by the cost performance requirements of the end use specification e.g. underground pipe, window frames, intravenous tubing and flooring all have very different ingredients to suit their performance requirements.

Perhaps something along those lines that is required to be food safe would work the same way (be very stable, avoiding the "slipped dowel"). What popped up in my head was canned frosting. I don't buy that for cakes I make, but I could make something with it and take it to work (they will eat anything). Then cut the top lip and bottom off the plastic "can" (to the height that you want) and use that to hold up the second (third, etc.) tier. Maybe I'll try it.

My brother is a plumber and he says PVC is not food safe, we've discussed this topic before!  Like when I've suggested he help me with some structure!

I wouldn't take the chance with it, even though Buddy Velastro does it all the time - sometimes covered in rkt and sometimes not.

Theresa

Honestly, that wall thickness [and the hassle of cutting it] is really overkill.  It's definitely sturdy, no doubt about that.

Pretty much ANY hollow column of a decent bore--like bubble tea straws, Wilton hollow dowels or pillars, SPS columns, whatever--will have the same "holding" power.  It's the physics of the shape, not the thickness of the wall. 

A thick walled "straw/dowel" with a tiny hole is no better than a skinny stick [wooden dowel] because both can be gradually bowed from pressure and can slip easily.  A hollow column with a large hole can't bow that way and isn't prone to slippage because of the cake plug that anchors it in place--that's the beauty of it.

I've always wondered about the food safety value of PVC.  My husband was in the heating/cooling/plumbing trade and he wouldn't let me use it for cakes.  I'm excited to see what Dawn Butler is going to make with her new product, Cake Frame.  It kinda looks like SPS with the ability to make shapes and complex cakes with it.  I do love me some SPS so I hope this is a great option for me to do gravity defying cakes!